Summary. —The five-fold decrease with increasing energy in the observed ratio between the observed energy in the cores of air showers and the total number of electrons in these showers suggests a large dissipation of the primary energy in a shower as the observed number of electrons exceeds 106. The apparent existence of events wherein thousands of pions of 3–6 GeV are generated in the colliding nucleon-nucleon c.m. system, suggests the formation of a “united gluon field”, without quarks, in the c.m. system of the colliding nucleons and its subsequent hadronization upon expansion, including passing through a quark-gluon plasma. PACS 95.85.Ry – Neutrino, muon, pion, and other elementary particles; cosmic rays. PACS 96.40.De – Composition, energy spectra, and interactions.
PACS 01.30.Cc – Conference proceedings.
1. – Air shower observation
The investigation of extensive air showers (EAS) has revealed a number of contradic-tion to the assumpcontradic-tion that the break of the EAS spectrum around an electron number Ne 106 is a break in the primarycosmic rayspectrum [1]. The spectra of the EAS generated byprimaryprotons deep in the atmosphere and of the showers generated by the primarycosmic raynuclei have no break (fig. 1). The absorption of the electron flux between atmosphere depths of 720 g/cm2 and 960 g/cm2 is different for showers with age parameter S < 0.7 and S > 1.05. The absorption lengths of the EAS with S < 0.7 in the atmosphere being λabs ≤ 90 g/cm2 and withS > 1.05 being λabs ≥ 160 g/cm2. This confirms the correct identification of these primarycosmic rayparticles as protons and heavier nuclei accordingly. Figure 2 shows that the assumption that the break in the
(∗) Paper presented at the Chacaltaya Meeting on Cosmic Ray Physics, La Paz, Bolivia, July 23-27, 2000.
c
Fig. 1. – Spectra of EAS with 0.75 ≤ S < 1.05 (crosses). S ≥ 1.05 (closed triangles), and
S < 0.75 (open circles) for two intervals of the zenith angle Θ: Θ < 25◦ for the three upper
spectra and Θ> 25◦for the three lower spectra.
EAS energyspectrum is connected with the break in the energyspectrum of primarypro-tons has to be accompanied bya second assumption about an increasing flux of primary nuclei. These two suppositions can be replaced bythe single proposition that there is a large increase in the multiplicityof the secondaryhadrons in inelastic nucleon-nucleon collisions at energies higher than 3–6 TeV in the nucleon-nucleon center-of-mass (c.m.) system. One can see in fig. 2 that the coefficient of connection between the primary proton energyand the observed number of electrons in the shower increases bymore than a factor of four.
The impossibilityto observe the inverse break [2] bymeans of the installation with the wide separated detectors is connected with the necessityto have the experimental data about electron flow in more than five detectors, which are placed up to an area of ∼ 104 m2 around the EAS core. This inverse break was confirmed in the hadron experiment [3].
An underestimation of the energies of the primaryparticles, which generate EAS with a number of electronsNe> 106can be seen in the experimental observed disappearance of primarynuclei at energies∼ 3–5 · 1018 eV instead of 5· 1019eV, as it was in the result of the resonance disintegration of nuclei in the collisions with relic protons [4].
The break in the electron number spectrum of EAS and, at higher energies, the return break, maybe understood in the context of: 1) the five-fold decrease in the relative energy in the EAS cores for showers with a number of electronsNe≥ 5·106, 2) the predominance of the showers absorbed between the breaks similar to the hadron-electron avalanches (fig. 2), and 3) the underestimation of the energybywhich one observes the relic cutoff
Fig. 2. – Integrated electron number spectrum of EAS at an atmosphere depth of 760 g/cm (+) and its two components with the different values of the absorption (Λa) of the electron number. Stroke straight lines conform to the expected spectrum of EAS in the case of the standard model of the hadron multiproduction.
of primarynuclei [4]. All of these experimental results together contradict the supposed existence of a break in the primarycosmic rayenergyspectrum at energies of about ∼ (2–3) · 1015 eV and suggest a significant increase of the multiplicityof the secondary hadrons at energies of the colliding nucleons higher than 3–6 TeV in the nucleon-nucleon c.m. system.
If this underestimation of the primaryenergyof the EAS beginning at the knee of the EAS spectrum with a number of electronsNe 106, is taken into account, then the energyspectrum derived from the satellite studies of cosmic rays at energiesE0 < 104 GeV can be extended up to 1010 GeV. Hence the energydependence of the total cosmic rayflux can be represented byF (E0) = (2.0±0.2)E−2.7±0.030 cm−2s−1sr−1GeV−1through this entire energyrange [5]. It should be noted here that this spectrum of the cosmic rays flux includes the galactic as well as the extragalactic cosmic rays.
Another particular feature of interest is the softness of the cosmic rayspectrum F (≥ E0)∼ E0−1.7in comparison with the spectra ofγ-quanta from the local galactic and extragalactic sourcesF (≥ Eγ)∼ Eγ1.4±0.1 [6]. Besides, different sources have their limit of the highest energies for the acceleration of protons and nuclei. One can suppose that a unified energyspectrum of the cosmic rays can be formed in extragalactic space by energylosses through the repeated elastic collisions with relic photons.
2. – The hadron high multiplicity production in the c.m. system and the revelation of the quark-gluon plasma
The experimental results presented in the previous section (fig. 3) lead to a conclusion concerning the increase of the multiplicityof secondaryhadrons in high-energyinelastic hadron collisions, but do not provide a quantitative estimate of this increase. A new hard claim concerning the properties of hadron inelastic collisions emerged after the discovery of a large number of non-relativistic neutrons with a significant time delayrelative to the detection of the main EAS front of the relativistic particles [6] (fig. 3). It is possible that
Fig. 3. – Temporal distributions of the number of neutronI for the different total multiplicity of neutrons detected in monitor: 316–400, 500–630, 794–1000, 1258–1584, 1995–2511 (from bottom to top).
the observed hundred-fold increase in the number of non-relativistic neutrons corresponds to a comparable increase in the hadron stream close to the observation level. And this sharp increase of the hadron stream in the cascade maybe due the high-multiplicity production of hadrons in the first interaction of the primaryprotons with nuclei of the atmosphere. This extremelyhigh hadron multiplicityis possible if half of the energy in the c.m. system of the colliding nucleons is distributed among the secondary pions with extreme low energies in the c.m. system. If one supposes the energies of secondary pions in the c.m. system to be 0.5 GeV or 5 GeV for the secondary nucleons, we obtain the tenfold difference in the multiplicityafter the first interaction but approximatelythe same number of hadrons after three or, at the generation of protons with energies of 5 GeV in the c.m. system, four generations of the following cascades in the atmosphere. An advantage of this experiment is that it deliberatelyincludes an observation threshold for EAS with primaryenergies below the threshold of the change in the multi-hadron production discussed above. The analysis of 848 showers with electron numbersNe> 106 revealed 25 showers, which were accompanied bya large number of neutrons: from 1260 up 2510 neutrons in one section of the neutron monitor within a time interval of 3.6 ms. It is a new phenomenon, which was not observed at smaller energies. The problem of explaining such showers with long delays relative to the shower front and the double-peaked shape of the neutron arrival time distribution can be solved onlyby the proposition of the change in the process of the generation of the EAS. The lateral distribution of these non-relativistic neutrons is estimated to range up to 20 m and the total number of the non-relativistic neutrons is interpreted to exceed 10% of the number of electrons in showers with Ne > 5 · 106. Such a neutron flux is possible if the first interaction of the primarycosmic rayproduces an extremelyhigh multiplicity of secondaryhadrons. This in turn maymean that the gluon fields of the colliding nucleons form a single excited gluon clot in the center-of-mass system of the colliding particles. The gluon clot then transforms into the quark-gluon plasma, and its subsequent
I am grateful to Prof. L. Jones for a great remark to this text, that enlarges this work. In particular, it induced to a wide revaluation of the multiplicityof secondary hadrons in the c.m. system of colliding nucleons.
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